---
title: "Team 2890 Swerve Modules — SDS MK4i"
tags:
  - hardware
  - drivetrain
  - swerve
  - 2890
type: hardware-spec
owner: 2890
status: active
sources:
  - "https://www.swervedrivespecialties.com/products/mk4i-swerve-module"
  - "https://andymark.com/products/sds-mk4i-swerve-modules"
  - "https://www.scribd.com/document/690437836/SDS-MK4i-Swerve-Modules-Assembly-Guide"
growth: tree
---

# SDS MK4i Swerve Module — Team 2890 Standard

## Overview

Team 2890 uses the **Swerve Drive Specialties MK4i** swerve module. This is the core drivetrain component — each robot has four modules, one per corner.

## Key Features

- **On-axis steering encoder** — zero backlash, module can be disassembled/reassembled without resetting encoder offset
- **Corner bias** — compact 4" × 4" internal frame width (MK4i has same corner bias as MK4n, different from MK4)
- **Full steering ratio:** 150/7:1 (passes through one gear pair, then a 64T belt pulley pair)
- **Mounting hardware:** Updated June 2023 — changed from 8-32 to **10-32 screws**
- **Wheel options:** Standard 4" wheel (can be replaced with 3" for weight savings)

## Drive Ratios

| Ratio | Best For | Notes |
|-------|----------|-------|
| **L1** | Standard full-weight competition robots | Most popular |
| **L2** | Standard full-weight competition robots | Most popular |
| **L3** | Lightweight robots | More aggressive, higher speed |

L1 and L2 are recommended for standard FRC robots. L3 is for lightweight builds only.

### Team 2890 — L1 and L3 (Field-Swappable)

Chris's team runs **L1 and L3 gear sets**, both driven by NEO Vortex motors. Gears swap in the field to change the drive ratio per event or strategy.

| Ratio | Stage 1 | Stage 2 | Stage 3 | Free Speed (Vortex) |
|-------|---------|---------|---------|---------------------|
| **L1** | 15T/22T | 20T/26T | 26T/36T | ~14.4 ft/s |
| **L3** | 15T/22T | 20T/26T | 26T/36T | ~12.8 ft/s |

**L1 = faster, less torque.** **L3 = more torque, slightly slower.** Swap based on game demands — L1 for high-speed defense, L3 for climbing/pushing.

*(Gear ratio diagram: `mk4i-gear-ratios.png`)*

## Connection to Training

**For students learning swerve:** This module uses a 1/2" hex output shaft. Understanding hex shafts and how they transfer torque is fundamental mechanical knowledge. Students should also understand:
- Why steering ratio matters (fast steering vs. precision)
- What "corner bias" means for turning radius
- How the belt drive multiplies torque from motor to wheel

**Related training modules:**
- [[motor-basics]] — understanding Kv, torque, current relationships
- [[frc-drivetrain-training]] — swerve kinematics and control
- [[2890-codebase-index]] — how the code configures these modules

## Source Links

- Product page: https://www.swervedrivespecialties.com/products/mk4i-swerve-module
- Assembly guide (PDF): https://www.scribd.com/document/690437836/SDS-MK4i-Swerve-Modules-Assembly-Guide
- AndyMark: https://andymark.com/products/sds-mk4i-swerve-modules

## Notes for MrC

Chris uses these modules with NEO Vortex motors and SPARK Flex controllers. The full stack is: **MK4i + NEO Vortex + SPARK Flex + YAGSL**. The YAGSL library (Yet Another Gyro Library) handles the swerve math and motor control in code.
